DSpace Collection:http://hdl.handle.net/2122/158
Sun, 02 Aug 2015 22:27:27 GMT2015-08-02T22:27:27ZEnhanced primary productivity and magnetotactic bacterial production in response to middle Eocene warming in the Neo-Tethys Oceanhttp://hdl.handle.net/2122/9962
Title: Enhanced primary productivity and magnetotactic bacterial production in response to middle Eocene warming in the Neo-Tethys Ocean
Authors: Savian, J.; Universidade Federal do Rio Grande do Sul, Brasil; Jovane, L.; Universidade de São Paulo, Brasil; Frontalini, F.; Università degli Studi di Urbino “Carlo Bo”; Trindade, R. I. F; Universidade de São Paulo, Brasil; Coccioni, R.; Università degli Studi di Urbino “Carlo Bo”; Bohaty, S. M.; University of Southampton; Wilson, P. A.; University of Southampton; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Roberts, A. P.; The Australian National University, Australia; Catanzariti, R.; Istituto di Geoscienze e Georisorse CNR, Pisa; Iacoviello, F.; Universidade de São Paulo, Brasil
Abstract: Earth's climate experienced a warming event known as the Middle Eocene Climatic Optimum (MECO) at ~ 40 Ma, which was an abrupt reversal of a long-term Eocene cooling trend. This event is characterized in the deep Southern, Atlantic, Pacific and Indian Oceans by a distinct negative δ18O excursion over 500 kyr. We report results of high-resolution paleontological, geochemical, and rock magnetic investigations of the Neo-Tethyan Monte Cagnero (MCA) section (northeastern Apennines, Italy), which can be correlated on the basis of magneto- and biostratigraphic results to the MECO event recorded in deep-sea sections. In the MCA section, an interval with a relative increase in eutrophic nannofossil taxa (and decreased abundances of oligotrophic taxa) spans the culmination of the MECO warming and its aftermath and coincides with a positive carbon isotope excursion, and a peak in magnetite and hematite/goethite concentration. The magnetite peak reflects the appearance of putative magnetofossils, while the hematite/goethite apex is attributed to an enhanced detrital mineral contribution, likely as aeolian dust transported from the continent adjacent to the Neo-Tethys Ocean during a drier, more seasonal climate during the peak MECO warming. Based on our new geochemical, paleontological and magnetic records, the MECO warming peak and its immediate aftermath are interpreted as a period of high primary productivity. Sea-surface iron fertilization is inferred to have stimulated high phytoplankton productivity, increasing organic carbon export to the seafloor and promoting enhanced biomineralization of magnetotactic bacteria, which are preserved as putative magnetofossils during the warmest periods of the MECO event in the MCA section. Together with previous studies, our work reinforces the connection between hyperthermal climatic events and the occurrence (or increased abundance) of putative magnetofossils in the sedimentary record.Fri, 22 Aug 2014 22:00:00 GMThttp://hdl.handle.net/2122/99622014-08-22T22:00:00ZAntarctic Ice Sheet response to a long warm interval across Marine Isotope Stage31: Across-latitudinal study of iceberg-rafted debrishttp://hdl.handle.net/2122/9919
Title: Antarctic Ice Sheet response to a long warm interval across Marine Isotope Stage31: Across-latitudinal study of iceberg-rafted debris
Authors: Teitler, L.; California State University; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Warnke, D. A.; California State University; Filippelli, G. M.; Kupp, G.; Taylor, B.
Abstract: Constraining the nature of Antarctic Ice Sheet (AIS) response to major past climate changes may provide a window onto future ice response and rates of sea level rise. One approach to tracking AIS dynamics, and differentiating whole system versus potentially heterogeneous ice sheet sector changes, is to integrate multiple climate proxies for a specific time slice across widely distributed locations. This study presents new iceberg-rafted debris (IRD) data across the interval that includes Marine Isotope Stage 31 (MIS 31: 1.081–1.062 Ma, a span of ∼19kyr; Lisiecki and Raymo, 2005), which lies on the cusp of the mid-Brunhes climate transition (as glacial cycles shifted from ∼41,000 yr to ∼100,000 yr duration). Two sites are studied—distal Ocean Drilling Program (ODP) Leg 177 Site 1090 (Site 1090) in the eastern subantarctic sector of the South Atlantic Ocean, and proximal ODP Leg 188 Site 1165 (Site 1165), near Prydz Bay, in the Indian Ocean sector of the Antarctic margin. At each of these sites, MIS 31 is marked by the presence of the Jaramillo Subchron (0.988–1.072Ma; Lourens et al., 2004) which provides a time-marker to correlate these two sites with relative precision. At both sites, records of multiple climate proxies are available to aid in interpretation. The presence of IRD in sediments from our study areas, which include garnets indicating a likely East Antarctic Ice Sheet (EAIS) origin, supports the conclusion that although the EAIS apparently withdrew significantly over MIS 31 in the Prydz Bay region and other sectors, some sectors of the EAIS must still have maintained marine margins capable of launching icebergs even through the warmest intervals. Thus, the EAIS did not respond in complete synchrony even to major climate changes such as MIS 31. Further, the record at Site 1090 (supported by records from other subantarctic locations) indicates that the glacial MIS 32 should be reduced to no more than a stadial, and the warm interval of Antarctic ice retreat that includes MIS 31 should be expanded to MIS 33-31. This revised warm interval lasted about 52 kyr, in line with several other interglacials in the benthic δ18Orecords stack of Lisiecki and Raymo(2005), including the super-interglacials MIS 11 (duration of 50 kyr) and MIS 5 (duration of 59 kyr). The record from Antarctica-proximal Site 1165, when interpreted in accord with the record from ANDRILL-1B, indicates that in these southern high latitude sectors, ice sheet retreat and the effects of warming lasted longer than at Site 1090, perhaps until MIS 27. In the current interpretations of the age models of the proximal sites, ice sheet retreat began relatively slowly, and was not really evident until the start of MIS 31. In another somewhat more speculative interpretation, ice sheet retreat began noticeably with MIS 33, and accelerated during MIS 31. Ice sheet inertia (the lag-times in the large-scale responses of major ice sheets to a forcing) likely plays an important part in the timing and scale of these events in vulnerable sectors of the AIS.Wed, 31 Dec 2014 23:00:00 GMThttp://hdl.handle.net/2122/99192014-12-31T23:00:00ZANNALS OF GEOPHYSICS: AD MAJORAhttp://hdl.handle.net/2122/9916
Title: ANNALS OF GEOPHYSICS: AD MAJORA
Authors: Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; De Michelis, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Muscari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Caprara, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Chiodetti, A. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Del Pezzo, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Gresta, S.; Univ Catania
Abstract: Annals of Geophysics (ISSN: 1593-5213; from 2010, 2037-416X) is a bimonthly international journal, which publishes scientific papers in the field of geophysics sensu lato. It derives from Annali di Geofisica (ISSN: 0365-2556), which commenced publication in January 1948 as a quarterly periodical devoted to general geophysics, seismology, Earth magnetism, and atmospheric studies....Tue, 31 Dec 2013 23:00:00 GMThttp://hdl.handle.net/2122/99162013-12-31T23:00:00ZMediterranean sapropels: a mere geological problem or a resource for the study of a changing planet?http://hdl.handle.net/2122/9667
Title: Mediterranean sapropels: a mere geological problem or a resource for the study of a changing planet?
Authors: Negri, A.; Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Ancona (Italy); Colleoni, F.; Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna (Italy); Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia
Abstract: Sapropels are sediments rich in organic carbon occurring cyclically in the Mediterranean marine records and whose origin has been matter of great debate during the last decades. While the first sapropels were found in eastern Mediterranean sediments from the Miocene period, in this paper we focus on the layers that were subsequently found in sediment cores of Pliocene to Quaternary age from the eastern Mediterranean mostly. Since the very beginning of the history of studies on sapropels, authors inferred that those lev- els, being interbedded as dark layers in more or less normal light “open marine” sediments, formed during short-lived but catastrophic alterations in Mediterranean oceanographic conditions, probably linked to broader climate changes. In this paper, the main hypotheses regarding the origin of those sediments are described and we highlight the importance of sapropel records for the study of climatic and oceanographic variability in the Mediterranean area in the context of global climate change.Sat, 31 Dec 2011 23:00:00 GMThttp://hdl.handle.net/2122/96672011-12-31T23:00:00ZAstronomical calibration of the Danian Stage (Early Paleocene) revisited: settling chronologies across the Atlantic and Pacific Oceanshttp://hdl.handle.net/2122/9233
Title: Astronomical calibration of the Danian Stage (Early Paleocene) revisited: settling chronologies across the Atlantic and Pacific Oceans
Authors: Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Westerhold, T.; MARUM - Center for Marine Environmental Sciences, Univ. of Bremen, Leobener Strasse, D-28359 Bremen, Germany; Pujalte, V.; Department of Stratigraphy and Paleontology, University of the Basque Country, UPV/EHU, PO Box 644, E-48080 Bilbao, Spain; Röhl, U.; MARUM - Center for Marine Environmental Sciences, Univ. of Bremen, Leobener Strasse, D-28359 Bremen, Germany; Kroon, D.; School of GeoSciences, Grant Institute, Univ. of Edinburgh, King's Buildings, West Mains Rd., Edinburgh, EH9 3JW, UK
Abstract: The astronomical time scale for the Paleocene is hampered
by some uncertainties including discrepant number of 405-kyr
eccentricity related cycles and correlation schemes among key
records being proposed by different authors (Westerhold et al.,
2008; Kuiper et al., 2008; Hilgen et al., 2010). Here we present
a new Danian correlation framework resolved at the ~100-kyr
short-eccentricity level between the land-based Zumaia and
Sopelana hemipelagic sections from the Basque Basin and
deep-sea records drilled during ODP Legs 198 (Shatsky Rise,
North Pacific) and 208 (Walvis Ridge, South Atlantic) that
reconciles both the magnetostratigraphy and the short and longeccentricity
cycle patterns among the records and, hence,
improves synchroneity of events. The correlation has been
aided by composite images from ODP cores and a new wholerock
13C isotope record at Zumaia while its original
magnetostratigraphy (Dinarès-Turell et al., 2003; 2010) is
reinforced by new data from Sopelana. Notably, we challenge
the correlation of the Pacific Sites 1209–1210 that were offset
by as much as one 405-kyr cycle in previous interpretations
(i.e., the Fasciculithus spp. LO, which approximates the
Danian–Selandian (D–S) boundary, and the “Top chron C27n”
climatic event were at odds between oceans in the
interpretation of Hilgen et al. (2010). It is found that the
Danian consists of 11 (and not 10) consecutive 405-kyr
eccentricity cycles.
The new consistent stratigraphic framework enables
accurate estimates to be made of ages for magnetostratigraphic
boundaries, bioevents, and sedimentation rates. Low
sedimentation rates appear common in all records in the mid-
Danian interval along the upper part of chron C28n, including
conspicuous condensed intervals in some of the oceanic
records that in the past have hampered the proper identification
of cycles. The new chronological framework, spanning a
duration of about 4.5 My, allows assessing the role of orbital
forcing on the paleoclimatic variability as registered by the
related isotope records. It appears clear that there exists a
periodic beat at the 100-ky and 405-ky eccentricity cycles
impressed in the record. The phase relationship between the
benthic isotope record and eccentricity is similar to patterns
documented for the Oligocene and Miocene, as indicated by
others, confirming the role of orbital forcing as the pace maker
for paleoclimatic variability on Milankovitch time scales. The
preferred tuning to the La2011 orbital solution provides
astronomically calibrated ages of 66.022±0.040 Ma and
61.607±0.040 Ma for the (D–S) and Cretaceous–Paleogene
(K–Pg) boundaries respectively. Finally, we envisage that the
Zumaia section, which already hosts the Selandian GSSP,
could serve as the global Danian stratotype.Mon, 30 Jun 2014 22:00:00 GMThttp://hdl.handle.net/2122/92332014-06-30T22:00:00ZData report: paleomagnetism and rock magnetism of sediments from offshore Canterbury Basin, IODP Expedition 317http://hdl.handle.net/2122/9208
Title: Data report: paleomagnetism and rock magnetism of sediments from offshore Canterbury Basin, IODP Expedition 317
Authors: Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Tinto, K.; Department of Geology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
Abstract: Paleomagnetic and rock magnetic analyses were conducted on
discrete samples from sediments drilled during Integrated Ocean
Drilling Program Expedition 317 in the Canterbury Basin offshore
New Zealand to assess the nature of magnetic remanence and to
evaluate the directional data for a magnetic reversal stratigraphy.
The sediments consist of relatively coarse grained lithologies from
shelf to slope settings. The presence of several hiatuses, together
with very low core recovery in some intervals as well as drillingrelated
magnetic overprints, prevented establishment of a good
shipboard magnetostratigraphy. In an effort to overcome some of
the magnetic shortcomings and to substantiate shipboard measurements
(overprints and partial demagnetization to 20 mT),
natural remanent magnetization and subsequent full stepwise alternating
field or thermal demagnetization measurements were
taken on 765 individual discrete samples from Holes U1351B (131
samples), U1352B/U1352C (485 samples), U1353B (54 samples),
and U1354B/U1354C (95 samples). Some rock magnetic measurements,
including thermomagnetic curves, were taken on a few
representative samples to acquire information on the magnetic
carriers. The remanence intensity of the sediments is relatively
low (usually 10–3 to 10–5 A/m) and often displays unstable behavior
upon demagnetization. Demagnetization data have been separated
into four different classes based on their quality. Classes 1
and 2 are of sufficient quality to be used for magnetostratigraphic
purposes and represent ~40% of the studied samples (although
some of them could still represent a steep magnetic drilling overprint).
Considering the calculated characteristic remanent magnetization
inclination, a number of polarity zones can be defined.
However, the fragmentary nature of the data set, mostly related to
core recovery in addition to detected and undetected sedimentary
hiatuses, makes determination of the precise position of the reversal
boundaries and their correlation to the geomagnetic polarity
timescale a difficult task. Nevertheless, when combined shipboard
and postcruise discrete measurements are placed within biostratigraphic
constraints, some magnetostratigraphic insights can potentially
refine the available age model. These insights include the
identification of the Matuyama/Brunhes boundary (C1r1r/C1n,
0.778 Ma) at all four sites, the Gauss/Matuyama boundary
(C2An.1n/C2r.2r, 2.581 Ma) in Hole U1351B, and also the position
of the Olduvai Subchron (C2n, 1.778–1.945 Ma) in Hole U1351B, which relates to the position of the classical
Pliocene/Pleistocene boundary.Tue, 06 May 2014 22:00:00 GMThttp://hdl.handle.net/2122/92082014-05-06T22:00:00ZIn Search of the Bartonian (Middle Eocene) GSSP (II): Preliminary Results from the Oyambre Section (Northern Spain)http://hdl.handle.net/2122/9206
Title: In Search of the Bartonian (Middle Eocene) GSSP (II): Preliminary Results from the Oyambre Section (Northern Spain)
Authors: Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Payros, A.; Fac. Ciencias, Estratigrafía-Paleontología, UPV/EHU, P.O Box 644, 48080 Bilbao, Spain; Monechi, S.; Dipartamento di Scienze della Terra, Università di Firenze, via La Pina 4, 50121 Florence, Italy; Orue-Etxebarria, X.; Fac. Ciencias, Estratigrafía-Paleontología, UPV/EHU, P.O Box 644, 48080 Bilbao, Spain; Ortiz, S.; Fac. Ciencias, Estratigrafía-Paleontología, UPV/EHU, P.O Box 644, 48080 Bilbao, Spain; Apellaniz, E.; Fac. Ciencias, Estratigrafía-Paleontología, UPV/EHU, P.O Box 644, 48080 Bilbao, Spain; Bernaola, G.; Department Ingeniería Minera, Esc. Univ. Ing. Téc. Minas, UPV/EHU, Rafael Moreno Pitxitxi 2, 48013 Bilbao, Spain
Editors: Rocha, R.; Faculdade de Ciências e Tecnologia Ciências da Terra, Universidade Nova de Lisboa; Pais, J.; Faculdade Ciências e Tecnologia Ciencias da Terra, Universidade Nova de Lisboa; Kullberg, J.C.; Ciências da Terra, Faculdade de Ciências e Tecnologia; Finney, S.; Geological Sciences, California State University Long Beach
Abstract: The Global Stratotype Section and Point (GSSP) for the base of the
Bartonian (middle Eocene) stage is as yet undefined. Here, we assess the GSSP
potential of the La Acebosa Formation exposed on the eastern side of the Cape of
Oyambre (San Vicente de la Barquera, province of Cantabria, northern Spain).
Sedimentological and benthic foraminiferal data indicate that the La Acebosa
Formation represents a bathyal environment related to a deepening, eastwardfacing
slope. Preliminary planktic foraminiferal and calcareous nannofossil results
show that the upper part of the section corresponds to zones E11 and CP14a,
respectively, and thus could include the Lutetian–Bartonian boundary. Although
the quality of demagnetization is quite poor, preliminary magnetostratigraphic data
suggest that Chron C19n, which is most likely to define the Bartonian GSSP, could
be recorded in the upper part of the La Acebosa Formation. A denser magnetostratigraphic
and biostratigraphic sampling is required in the upper part of this unit
in order to accurately identify Chron C19n and to establish the sequence of events
across the Lutetian–Bartonian transition.Sun, 30 Jun 2013 22:00:00 GMThttp://hdl.handle.net/2122/92062013-06-30T22:00:00ZIn Search of the Bartonian (Middle Eocene) GSSP (I): Potential in the Basque–Cantabrian and Aquitanian Basins (Western Pyrenees)http://hdl.handle.net/2122/9205
Title: In Search of the Bartonian (Middle Eocene) GSSP (I): Potential in the Basque–Cantabrian and Aquitanian Basins (Western Pyrenees)
Authors: Payros, A.; Estratigrafía-Paleontología, Fac. Ciencias, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain; Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Orue-Etxebarria, X.; Estratigrafía-Paleontología, Fac. Ciencias, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain; Monechi, S.; Dipartamento di Scienze Della Terra, Università di Firenze, Via La Pina 4, 50121 Florence, Italy; Ortiz, S.; Estratigrafía-Paleontología, Fac. Ciencias, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain; Apellaniz, E.; Estratigrafía-Paleontología, Fac. Ciencias, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain; Bernaola, G.; Dept. Ingeniería Minera, Esc, Univ. Ing. Téc. Minas, UPV/EHU, Rafael Moreno Pitxitxi 2, 48013 Bilbao, Spain
Editors: Rocha, R.; Faculdade de Ciências e Tecnologia Ciências da Terra, Universidade Nova de Lisboa; Pais, J.; Faculdade Ciências e Tecnologia Ciencias da Terra, Universidade Nova de Lisboa; Kullberg, J.C.; Ciências da Terra, Faculdade de Ciências e Tecnologia; Finney, S.; Geological Sciences, California State University Long Beach
Abstract: The Global Stratotype Section and Point (GSSP) for the base of the
Bartonian (middle Eocene) stage is as yet undefined. Herein we assess the GSSP
potential of the successions found in the Basque–Cantabrian and Aquitanian basins
(western Pyrenees). On the basis of the available data, no outcrop in the Biarritz
and Pamplona areas fulfilled the requirements outlined by the International
Commission on Stratigraphy. However, the succession exposed on the eastern side
of the Cape of Oyambre (San Vicente de la Barquera, province of Cantabria,
northern Spain) did so, and yielded positive preliminary results.Sun, 30 Jun 2013 22:00:00 GMThttp://hdl.handle.net/2122/92052013-06-30T22:00:00ZSettling the Danian Astronomical Time Scale: A Prospective Global Unit Stratotype at Zumaia, Basque Basinhttp://hdl.handle.net/2122/9204
Title: Settling the Danian Astronomical Time Scale: A Prospective Global Unit Stratotype at Zumaia, Basque Basin
Authors: Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Westerhold, T.; MARUM—Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany; Pujalte, V.; Department of Stratigraphy and Paleontology, University of the Basque Country, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain; Röhl, U.; MARUM—Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany; Kroon, D.; School of GeoSciences, Grant Institute, University of Edinburgh, King’s Buildings, West Mains Road, Edinburgh, EH9 3JW, UK
Editors: Rocha, R.; Faculdade de Ciências e Tecnologia Ciências da Terra, Universidade Nova de Lisboa; Pais, J.; Faculdade Ciências e Tecnologia Ciencias da Terra, Universidade Nova de Lisboa; Kullberg, J.C.; Ciências da Terra, Faculdade de Ciências e Tecnologia; Finney, S.; Geological Sciences, California State University Long Beach
Abstract: We present a new Danian correlation framework between the land-based
Zumaia and Sopelana sections from the Basque Basin and marine-based sections
drilled during ODP Legs 198 (Shatsky Rise, North Pacific) and 208 (Walvis Ridge,
South Atlantic) that reconciles magnetostratigraphy and the short and long eccentricity
cycle patterns among the records. A new whole-rock d13C isotope record at
Zumaia is compared to that of Site 1262. This allows the question of whether the
Danian consists of 10 or 11 consecutive 405-kyr eccentricity cycles to be tested. The
new consistent stratigraphic framework enables accurate estimates to be made of
ages for magnetostratigraphic boundaries, bioevents, and sedimentation rates. Low
sedimentation rates appear common in all records in the mid-Danian interval along
the upper part of chron C28n, including conspicuous condensed intervals in some of
the oceanic records that in the past have hampered the proper identification of
cycles. Notably, we challenge the correlation to the Pacific Sites 1209–1210 that
were offset by as much as one 405-kyr cycle in previous interpretations (i.e., the
Fasciculithus spp. LO, which approximates the Danian–Selandian boundary, and
the TC27n event were at odds between oceans in the interpretation of Hilgen et al.
2010). Finally, we envisage that the Zumaia section, which already hosts the
Selandian GSSP, could serve as the global Danian stratotype.Sun, 30 Jun 2013 22:00:00 GMThttp://hdl.handle.net/2122/92042013-06-30T22:00:00ZExtending Back the Palaeogene Astronomical Time Scale: An Integrated Analysis of the Upper Maastrichtian Strata in the Basque Basinhttp://hdl.handle.net/2122/9199
Title: Extending Back the Palaeogene Astronomical Time Scale: An Integrated Analysis of the Upper Maastrichtian Strata in the Basque Basin
Authors: Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Pujalte, V.; Department of Stratigraphy and Paleontology, University of the Basque Country, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain; Stoykova, K.; Department of Paleontology and Stratigraphy, Geological Institute, Bulgarian Academy of Science, BG-1113 Sofia, Bulgaria; Elorza, J.; Department of Mineralogy and Petrology, University of the Basque Country, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain
Editors: Rocha, R.; Faculdade de Ciências e Tecnologia Ciências da Terra, Universidade Nova de Lisboa; Pais, J.; Faculdade Ciências e Tecnologia Ciencias da Terra, Universidade Nova de Lisboa; Kullberg, J. C.; Ciências da Terra, Faculdade de Ciências e Tecnologia; Finney, S.; Geological Sciences, California State University Long Beach
Abstract: We present a comprehensive, integrated, cyclo–magnetostratigraphic analysis and study of the calcareous nannofossils of the upper Maastrichtian hemipelagic succession in three sections of the Basque Basin (Zumaia, Sopelana, and Hendaia). The sections were correlated at a bed-by-bed scale through careful analysis of the lithological stacking pattern and significant sedimentary features. For spectral analysis, we used an available carbonate proxy record spanning 64 m of section below the K–Pg (Cretaceous–Palaeogene) boundary at Zumaia containing 72 precession-related limestone–marl couplets. The continuous wavelet spectrum helped to determine and visualize the orbital forcing at both the short (~100 kyr) and long (405 kyr) eccentricity bands. We applied bandpass Gaussian filters to the carbonate record to extract the relevant periodicities and provide a cycle-numbering scheme starting at the K–Pg boundary. The full hierarchy of precession cycles and eccentricity-related bundles was then extended towards the base of the Zumaia section, which contains 33 short eccentricity-related bundles, thus spanning more than 3 Myr. The C31r–C31n chron boundary (estimated to occur at ~3.08 Myr prior to the K–Pg boundary) in the lower part of the succession was determined unambiguously in all three sections studied, although the C30n–C29r reversal could not be determined due to a pervasive reverse magnetization acting on the purplish lithologies in the upper part of the succession. Relevant calcareous plankton bioevents were able to be accurately placed on the cyclo–magnetostratigraphic template. The cyclostratigraphic framework also allowed us to estimate the duration of previously defined sea-level-related, third-order depositional sequences in the basin, which appear to be strongly paced by the long-term 1.2 Myr obliquity amplitude modulating cycle.Sun, 30 Jun 2013 22:00:00 GMThttp://hdl.handle.net/2122/91992013-06-30T22:00:00Z